Thanks for getting back and providing an update, @octopuswindowcle.

Right now, able to change/edit a pay period of a processed paycheck is currently unavailable in QuickBooks Online (QBO). As a workaround, you can delete and recreate them instead. To do this, let's pull up the Paycheck List report to serve as your guide. 

Here's how:

1. In the left menu, click Reports.
2. Type in Paycheck List on the search bar.
3. Click the Funnel icon drop-down to choose a date.
4. Put a checkmark on the paychecks you need to delete.
5. Click Delete.

Once done, to recreate them with the correct pay periods, follow the below steps:

1. In the left menu, click Payroll.
2. Go to the Employees tab.
3. Click Run payroll on the upper right, then pick an employee.
4. Enter the necessary information.
5. Select Preview payroll. 
6. Click Submit payroll.

To learn more about what you can and can't be edited on a paycheck in QBO, see this article: Change an employee paycheck.

Please know that I'm here anytime you have other concerns. Feel free to reach back out. Have a great day.